In recent years, light-emitting-diodes (LEDs) have emerged as a new technology for illumination and lighting applications. LEDs have potential advantages over fluorescent lamps in that they may be more efficient, may produce less heat, may have longer lifetimes, and may function more efficiently at cold temperatures. For these reasons and others, there has been a recent effort to incorporate LEDs into lighting applications, such as retrofit chandelier or candelabra lamps.
An example of a known LED-based lamp is discussed in U.S. Patent Application Publication No. 2010/0208488 (Luo). FIG. 1 shows a known light bulb 1, which is discussed in Luo. The light bulb 1 has an envelope 5 that encompasses a light pipe 2, a base 4, and a reflector 3. FIG. 2 shows the light pipe 2 of FIG. 1. An LED (not shown) is disposed within a hemispherical recess 6 at a lower end of the light pipe 2. The lateral side of the light pipe is a tapered cylinder 7.
Other examples of known LED-based lamps are discussed in U.S. Patent Application Publication No. 2012/0147611 (Huang et al.), U.S. Patent Application Publication No. 2010/0097821 (Huang et al.), U.S. Pat. No. 7,083,315 (Hansler et al.), U.S. Patent Application Publication No. 2009/0129230 (Grotsch), and U.S. Pat. No. 6,356,394 (Glienicke).